FIG. 1 illustrates a relay node (RN) and UEs located in the area of one eNB in a wireless communication system. A relay node refers to a node that receives a signal transmitted from a source node and wirelessly relays the signal to a destination node. The relay node can be considered for improvement of data rates of UEs, group mobility, temporary network disposition, throughput improvement in a cell edge area and/or provision of coverage in a new area. A UE can directly communicate with the eNB or perform communication with the eNB over two hops through the relay node.
The relay node transmits data received from the eNB to a UE located in the area of the relay node and transmits data received from the UE to the eNB. In the following description, a radio link between an eNB and a relay node is referred to as a backhaul link, a link from the eNB to the relay node is referred to as a backhaul downlink and a link from the relay node to the eNB is referred to as a backhaul uplink for convenience. In addition, a radio link between a relay node and a UE is referred to as an access link, a link from the relay node to the UE is referred to as an access downlink and a link from the UE to the relay node is referred to as an access uplink.